Tree breeding is the application of genetic principles to the genetic improvement and management of forest trees. In contrast to the selective breeding of livestock, arable crops, and horticultural flowers over the last few centuries, the breeding of trees, with the exception of fruit trees, is a relatively recent occurrence. A typical forest tree breeding program starts with selection of superior phenotypes (plus trees) in a natural or planted forest. This application of mass selection improves the mean performance of the forest. Offspring is obtained from selected trees and grown in test plantations that act as genetic trials. Based on such tests the best genotypes among the parents can be selected. Selected trees are typically multiplied by either seeds or grafting and seed orchards are established when the preferred output is improved seed. Alternatively, the best genotypes can be directly propagated by cuttings or in-vitro methods and used directly in clonal plantations. The first system is frequently used in pines and other conifers, While the second is typical in some broadleaves (poplars, eucalypts and others). The objectives of a tree breeding program range from yield improvement and adaptation to particular conditions, to pest-resistance, wood characters etc. Currently, tree breeding is gaining new interest under the threat of Global Warming, and it is taking advantage of the fast development in plant genetics and genomics |
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Norway spruce breeding
Norway spruce [Picea abies (L.) Karst.] is one of the most commercially important European coniferous species, and long-term, national breeding programmes for the species are being pursued in several countries, aiming at improving both its productivity and its quality.
It is a multipurpose species in the sense that the wood is used for a wide range of commodities, such as joinery products, furniture, composites and veneer.
However, those with the largest economic impact are solid wood products and pulp and paper products.The majority of Norway spruce sawn timber is used for structural purposes (Baudin 1989). Such timber must be suitable for use in construction, and in many cases it must carry a substantial load. Therefore, the quality of structural timber may be defined in terms of stability, strength and.The key properties determining these quality traits are spiral grain (grain angle), knot size and distribution, wood density and microfibril angle (MFA) in the secondary cell wall, as discussed by various authors,e.g. Dinwoodie (2000) and Forsberg& Warensjörn(2001).
For pulp and paper, tracheid structure and wood chemical composition are major determinants of quality. However, detailed requirements with respect to tracheid structure may vary according to the specific processes or paper assortments concerned.
It is a multipurpose species in the sense that the wood is used for a wide range of commodities, such as joinery products, furniture, composites and veneer.
However, those with the largest economic impact are solid wood products and pulp and paper products.The majority of Norway spruce sawn timber is used for structural purposes (Baudin 1989). Such timber must be suitable for use in construction, and in many cases it must carry a substantial load. Therefore, the quality of structural timber may be defined in terms of stability, strength and.The key properties determining these quality traits are spiral grain (grain angle), knot size and distribution, wood density and microfibril angle (MFA) in the secondary cell wall, as discussed by various authors,e.g. Dinwoodie (2000) and Forsberg& Warensjörn(2001).
For pulp and paper, tracheid structure and wood chemical composition are major determinants of quality. However, detailed requirements with respect to tracheid structure may vary according to the specific processes or paper assortments concerned.
Scots pine breeding
In Scandinavia, Scots pine is an important source of raw material especially for the sawn timber industry, but also for the pulp and paper industry.
In these circumstances, the interaction of the prevailing temperature conditions during the growing season and its length, availability of water, nutrients and light has an effect on the overall growth of trees, and the properties of stem and wood in tree stands.
On the other hand, silvicultural management, such as selection of proper genetic entries and species, spacing, thinning, fertilisation and rotation length, can be used to modify the growth of trees within stands and, thus, affect stem wood production in tree stands.
In these circumstances, the interaction of the prevailing temperature conditions during the growing season and its length, availability of water, nutrients and light has an effect on the overall growth of trees, and the properties of stem and wood in tree stands.
On the other hand, silvicultural management, such as selection of proper genetic entries and species, spacing, thinning, fertilisation and rotation length, can be used to modify the growth of trees within stands and, thus, affect stem wood production in tree stands.